Answer: (-x,y)
Step-by-Step Explanation:
In geometry, when a figure is reflected over particularly the y-axis, one coordinate will change.
The y coordinate will remain the same, not value wise. (positive in your case.)
Wherease the x coordinate will be the opposite additive inverse.
For example if you have (4,3) and it is reflected over the y-axis, the new coordinate will be (-4,y)
Hope this helps! :)